Organic electroluminescent device, organic electroluminescent display device including the same, and organometallic compound for organic electroluminescent device

ABSTRACT

An organic electroluminescent device includes a first electrode, a hole transport region provided on the first electrode, an emission layer provided on the hole transport region, an electron transport region provided on the emission layer, and a second electrode provided on the electron transport region, wherein the emission layer includes an organometallic compound represented by Formula 1.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2018-0013609, filed on Feb. 2, 2018, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND Field

Exemplary embodiments/implementations of the invention relate generallyto an organic electroluminescent device, an organic electroluminescentdisplay device including the same, and an organometallic compound usedin the organic electroluminescent device.

Discussion of the Background

The development of an organic electroluminescent display as an imagedisplay is being actively conducted. The organic electroluminescentdisplay is different from a liquid crystal display and is a so calledself-luminescent display accomplishing displays via the recombination ofholes and electrons injected from a first electrode and a secondelectrode in an emission layer and via light emission from a luminescentmaterial including an organic compound in the emission layer.

As an organic electroluminescent device, an organic device including,for example, a first electrode, a hole transport layer disposed on thefirst electrode, an emission layer disposed on the hole transport layer,an electron transport layer disposed on the emission layer, and a secondelectrode disposed on the electron transport layer is well known. Holesare injected from the first electrode, and the injected holes move viathe hole transport layer and are injected into the emission layer.Meanwhile, electrons are injected from the second electrode, and theinjected electrons move via the electron transport layer and areinjected into the emission layer. The holes and electrons injected intothe emission layer recombine to produce excitons in the emission layer.The organic electroluminescent device emits light using light generatedby the transition of the excitons to a ground state. In addition, anembodiment of the configuration of the organic electroluminescent deviceis not limited thereto, but various modifications may be possible.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Exemplary embodiments of the inventive concepts provide an organicelectroluminescent device, an organic electroluminescent display deviceincluding the same, and an organometallic compound for an organicelectroluminescent device. More particularly, the exemplary embodimentsprovide an organic electroluminescent device which is capable ofemitting near-infrared rays, an organic electroluminescent displaydevice including the same, and an organometallic compound used as aluminescent material emitting near-infrared rays.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

An exemplary embodiment of the inventive concept discloses an organicelectroluminescent device including a first electrode, a hole transportregion provided on the first electrode, an emission layer provided onthe hole transport region, an electron transport region provided on theemission layer, and a second electrode provided on the electrontransport region, wherein the emission layer includes an organometalliccompound represented by the following Formula 1:

In Formula 1, R₁ and R₂ are each independently a hydrogen atom, adeuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted aryl group having 6 to30 carbon atoms for forming a ring, or a substituted or unsubstitutedheteroaryl group having 2 to 30 carbon atoms for forming a ring, or maybe combined with an adjacent group to form a ring, “p” is an integer of0 to 4, “q” is an integer of 0 to 3, “n” is 1 or 2, M is Pt, Ir or Os,and L₁ is a bidentate ligand.

In an exemplary embodiment, L₁ may be represented by one of thefollowing Formulae 2-1 to 2-6:

In Formulae 2-1 to 2-6, X₁ is O or NR′, X₂ to X₄ are each independentlyCH, N, or NR₂₁, Y₁ is a direct linkage or CH, R′, and R₃ to R₂₁ are eachindependently a hydrogen atom, a deuterium atom, a substituted orunsubstituted alkyl group having 1 to 10 carbon atoms, or a substitutedor unsubstituted aryl group having 6 to 30 carbon atoms for forming aring, or may be combined with an adjacent group to form a ring, “a”,“c”, “d”, “e”, “g” and “j” are each independently an integer of 0 to 4,“b” is an integer of 0 to 5, “f” and “i” are an integer of 0 to 3, and“h” is an integer of 0 to 2.

In an exemplary embodiment, M may be Pt.

In an exemplary embodiment, Formula 1 may be represented by one of thefollowing Formulae 1-1 to 1-3:

In Formulae 1-1 to 1-3, M, R₂, L₁, “n” and “q” are the same as describedabove.

In an exemplary embodiment, the emission layer may include a host and adopant and emit near-infrared rays in a wavelength region of about 750nm to about 1,000 nm, and the dopant may include the organometalliccompound represented by Formula 1.

In an exemplary embodiment of the inventive concept, an organicelectroluminescent display device includes a first pixel including afirst organic electroluminescent device which emits first visible rays,a second pixel including a second organic electroluminescent devicewhich emits second visible rays, a third pixel including a third organicelectroluminescent device which emits third visible rays, and a fourthpixel including a fourth organic electroluminescent device which emitsnear-infrared rays, wherein the fourth organic electroluminescent deviceincludes an emission layer including the above-described organometalliccompound represented by Formula 1.

In an exemplary embodiment of the inventive concept, the above-describedorganometallic compound represented by Formula 1 is provided.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinventive concepts, and together with the description serve to explainthe inventive concepts.

FIG. 1 is a cross-sectional view schematically illustrating an organicelectroluminescent device according to an exemplary embodiment of theinventive concept.

FIG. 2 is a cross-sectional view schematically illustrating an organicelectroluminescent device according to an exemplary embodiment of theinventive concept.

FIG. 3 is a perspective view of an organic electroluminescent displaydevice according to an exemplary embodiment of the inventive concept.

FIG. 4 is a circuit diagram of a pixel included in an organicelectroluminescent display device according to an exemplary embodimentof the inventive concept.

FIG. 5 is a plan view showing a pixel included in an organicelectroluminescent display device according to an exemplary embodimentof the inventive concept;

FIG. 6 is a cross-sectional view taken along a region II-II′ of FIG. 5.

FIG. 7 is a cross-sectional view taken along a region I-I′ of FIG. 3.

FIG. 8 is a plan view illustrating the relation of a pixel layout of anorganic electroluminescent display device according to an exemplaryembodiment of the inventive concept.

FIG. 9 is a plan view illustrating the relation of a pixel layout of anorganic electroluminescent display device according to an exemplaryembodiment of the inventive concept.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments or implementations of theinvention. As used herein “embodiments” and “implementations” areinterchangeable words that are non-limiting examples of devices ormethods employing one or more of the inventive concepts disclosedherein. It is apparent, however, that various exemplary embodiments maybe practiced without these specific details or with one or moreequivalent arrangements. In other instances, well-known structures anddevices are shown in block diagram form in order to avoid unnecessarilyobscuring various exemplary embodiments. Further, various exemplaryembodiments may be different, but do not have to be exclusive. Forexample, specific shapes, configurations, and characteristics of anexemplary embodiment may be used or implemented in another exemplaryembodiment without departing from the inventive concepts.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. When anexemplary embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. Further, the DR1-axis, theDR2-axis, and the DR3-axis are not limited to three axes of arectangular coordinate system, such as the x, y, and z-axes, and may beinterpreted in a broader sense. For example, the DR1-axis, the DR2-axis,and the DR3-axis may be perpendicular to one another, or may representdifferent directions that are not perpendicular to one another. For thepurposes of this disclosure, “at least one of X, Y, and Z” and “at leastone selected from the group consisting of X, Y, and Z” may be construedas X only, Y only, Z only, or any combination of two or more of X, Y,and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, theterm “and/or” includes any and all combinations of one or more of theassociated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element discussed below could be termed asecond element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Various exemplary embodiments are described herein with reference tosectional and/or exploded illustrations that are schematic illustrationsof idealized exemplary embodiments and/or intermediate structures. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should notnecessarily be construed as limited to the particular illustrated shapesof regions, but are to include deviations in shapes that result from,for instance, manufacturing. In this manner, regions illustrated in thedrawings may be schematic in nature and the shapes of these regions maynot reflect actual shapes of regions of a device and, as such, are notnecessarily intended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

The above objects, other objects, features and advantages of theinventive concept will be easily understood from preferred exemplaryembodiments with reference to the accompanying drawings. The inventiveconcept may, however, be embodied in different forms and should not beconstrued as limited to the embodiments set forth herein.

Like reference numerals refer to like elements for explaining eachdrawing. In the drawings, the sizes of elements may be enlarged forclarity of the inventive concept. It will be understood that, althoughthe terms first, second, etc. may be used herein to describe variouselements, these elements should not be limited by these terms. Theseterms are only used to distinguish one element from another element. Forexample, a first element discussed below could be termed a secondelement, and similarly, a second element could be termed a firstelement. As used herein, the singular forms are intended to include theplural forms as well, unless the context clearly indicates otherwise.

It will be further understood that the terms “comprises” or“comprising,” when used in this specification, specify the presence ofstated features, numerals, steps, operations, elements, parts, or acombination thereof, but do not preclude the presence or addition of oneor more other features, numerals, steps, operations, elements, parts, ora combination thereof. It will also be understood that when a layer, afilm, a region, a plate, etc. is referred to as being “on” another part,it can be “directly on” the other part, or intervening layers may alsobe present. On the contrary, when a layer, a film, a region, a plate,etc. is referred to as being “under” another part, it can be “directlyunder” the other part, or intervening layers may also be present.

First, referring to FIGS. 1 and 2, an organic electroluminescent deviceaccording to an exemplary embodiment of the inventive concept will beexplained.

FIG. 1 is a cross-sectional view schematically illustrating an organicelectroluminescent device according to an exemplary embodiment of theinventive concept. FIG. 2 is a cross-sectional view schematicallyillustrating an organic electroluminescent device according to anexemplary embodiment of the inventive concept.

Referring to FIGS. 1 and 2, an organic electroluminescent device 10according to an exemplary embodiment of the inventive concept mayinclude a first electrode EL1, a hole transport region HTR, an emissionlayer EML, an electron transport region ETR, and a second electrode EL2.

The first electrode EL1 and the second electrode EL2 are oppositelydisposed, and between the first electrode EL1 and the second electrodeEL2, a plurality of organic layers may be disposed. The plurality of theorganic layers may include a hole transport region HTR, an emissionlayer EML and an electron transport region ETR.

The first electrode EL1 has electrical conductivity. The first electrodeEL1 may be a pixel electrode or an anode. The first electrode EL1 may bea transmissive electrode, a transflective electrode, or a reflectiveelectrode. If the first electrode EL1 is the transmissive electrode, thefirst electrode EL1 may be formed using a transparent metal oxide suchas indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO),and indium tin zinc oxide (ITZO). If the first electrode EL1 is thetransflective electrode or reflective electrode, the first electrode EL1may include Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca,LiF/Al, Mo, Ti, a compound thereof, or a mixture thereof (for example, amixture of Ag and Mg). Also, the first electrode EL1 may include aplurality of layers including the reflective layer or transflectivelayer formed using the above materials, and a transparent conductivelayer formed using ITO, IZO, ZnO, or ITZO. For example, the firstelectrode EL1 may have a three-layer structure of ITO/Ag/ITO. However,exemplary embodiments of the inventive concepts are not limited thereto.

The thickness of the first electrode EL1 may be from about 1,000 Å toabout 10,000 Å, for example from about 1,000 Å to about 3,000 Å.

The hole transport region HTR is provided on the first electrode EL1.The hole transport region HTR may include at least one of a holeinjection layer HIL, a hole transport layer HTL, a hole buffer layer, oran electron blocking layer. The thickness of the hole transport regionHTR may be, for example, from about 1,000 Å to about 1,500 Å.

The hole transport region HTR may have a single layer formed using asingle material, a single layer formed using a plurality of differentmaterials, or a multilayer structure including a plurality of layersformed using a plurality of different materials.

For example, the hole transport region HTR may have the structure of asingle layer such as a hole injection layer HIL and a hole transportlayer HTL, or may have a structure of a single layer formed using a holeinjection material and a hole transport material. In addition, the holetransport region HTR may have a structure of a single layer formed usinga plurality of different materials, or a structure laminated one by onefrom the first electrode EL1 of hole injection layer HIL/hole transportlayer HTL, hole injection layer HIL/hole transport layer HTL/hole bufferlayer, hole injection layer HIL/hole buffer layer, hole transport layerHTL/hole buffer layer, or hole injection layer HIL/hole transport layerHTL/electron blocking layer, without limitation.

The hole transport region HTR may be formed using various methods suchas a vacuum deposition method, a spin coating method, a cast method, aLangmuir-Blodgett (LB) method, an inkjet printing method, a laserprinting method, and a laser induced thermal imaging (LITI) method.

The hole injection layer HIL may include, for example, a phthalocyaninecompound such as copper phthalocyanine;N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine(DNTPD), 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine(m-MTDATA), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDATA),4,4′,4″-tris {N-(2-naphthyl)-N-phenylamino}-triphenylamine (2-TNATA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS),polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), polyaniline/camphorsulfonic acid (PANI/CSA), polyaniline/poly(4-styrenesulfonate)(PANI/PSS), N,N′-dinaphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB),triphenylamine-containing polyether ketone (TPAPEK),4-isopropyl-4′-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate,dipyrazino[2,3-f: 2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile(HAT-CN), etc.

The hole transport layer HTL includes, for example, carbazolederivatives such as N-phenyl carbazole and polyvinyl carbazole,fluorine-based derivatives,N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD), triphenylamine-based derivatives such as4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),N,N′-di(1-naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB),4,4′-cyclohexylidene bis[N,N-bis(4-methylphenyl)benzenamine] (TAPC),4,4′-bis[N,N′-(3-tolyl)amino]-3,3′-dimethylbiphenyl (HMTPD),1,3-bis(N-carbazolyl)benzene (mCP), etc.

The thickness of the hole transport region HTR may be from about 100 Åto about 10,000 Å, for example, from about 100 Å to about 1,000 Å. Ifthe hole transport region HTR includes both the hole injection layer HILand the hole transport layer HTL, the thickness of the hole injectionlayer HIL may be from about 100 Å to about 10,000 Å, for example, fromabout 100 Å to about 1,000 Å, and the thickness of the hole transportlayer HTL may be from about 30 Å to about 1,000 Å. If the thicknesses ofthe hole transport region HTR, the hole injection layer HIL, and thehole transport layer HTL satisfy the above-described ranges,satisfactory hole transport properties may be obtained withoutsubstantial increase of a driving voltage.

The hole transport region HTR may further include a charge generatingmaterial in addition to the above-described materials to improveconductivity. The charge generating material may be dispersed in thehole transport region HTR uniformly or non-uniformly. The chargegenerating material may be, for example, a p-dopant. The p-dopant may beone of quinone derivatives, metal oxides, or cyano group-containingcompounds, without limitation. For example, non-limiting examples of thep-dopant may include quinone derivatives such astetracyanoquinodimethane (TCNQ), and2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), metal oxidessuch as tungsten oxide, molybdenum oxide, etc., without limitation.

As described above, the hole transport region HTR may further include atleast one of a hole buffer layer or an electron blocking layer inaddition to the hole injection layer HIL and the hole transport layerHTL. The hole buffer layer may compensate a resonance distance accordingto the wavelength of light emitted from the emission layer EML andincrease light emission efficiency. Materials included in the holetransport region HTR may be used as materials included in the holebuffer layer. The electron blocking layer is a layer preventing electroninjection from the electron transport region ETR to the hole transportregion HTR.

The emission layer EML is provided on the hole transport region HTR. Thethickness of the emission layer EML may be, for example, from about 100Å to about 1,000 Å, or about 100 Å to about 300 Å. The emission layerEML may have a single layer formed using a single material, a singlelayer formed using a plurality of different materials, or a multilayerstructure having a plurality of layers formed using a plurality ofdifferent materials.

The emission layer EML included in the organic electroluminescent device10 according to an exemplary embodiment of the inventive concept is anemission layer emitting near-infrared rays. The emission layer EMLincludes a luminescent material of near-infrared rays. The emissionlayer EML includes an organometallic compound represented by Formula 1,which will be explained later.

Particulars on the material, the emission wavelength, etc. of theemission layer EML will be explained later.

The electron transport region ETR is provided on the emission layer EML.The electron transport region ETR may include at least one of anelectron blocking layer, an electron transport layer ETL, or an electroninjection layer EIL, without limitation.

The electron transport region ETR may have a single layer formed using asingle material, a single layer formed using a plurality of differentmaterials, or a multilayer structure including a plurality of layersformed using a plurality of different materials.

For example, the electron transport region ETR may have the structure ofa single layer such as an electron injection layer EIL and an electrontransport layer ETL, or a single layer structure formed using anelectron injection material and an electron transport material. Inaddition, the electron transport region ETR may have a single layerstructure formed using a plurality of different materials, or astructure laminated one by one from the emission layer EML of electrontransport layer ETL/electron injection layer EIL, or hole blockinglayer/electron transport layer ETL/electron injection layer EIL, withoutlimitation. The thickness of the electron transport region ETR may be,for example, from about 1,000 Å to about 1,500 Å.

The electron transport region ETR may be formed using various methodssuch as a vacuum deposition method, a spin coating method, a castmethod, a Langmuir-Blodgett (LB) method, an inkjet printing method, alaser printing method, and a laser induced thermal imaging (LITI)method.

If the electron transport region ETR includes the electron transportlayer ETL, the electron transport region ETR may include ananthracene-based compound. However, exemplary embodiments of theinventive concepts are not limited thereto. The electron transportregion may include, for example, tris(8-hydroxyquinolinato)aluminum(Alq₃), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene,2,4,6-tris(3′-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine,2-(4-(N-phenylbenzoimidazolyl-1-ylphenyl)-9,10-dinaphthylanthracene,1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi),2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP),4,7-diphenyl-1,10-phenanthroline (Bphen),3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ),4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ),2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD),bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-biphenyl-4-olato)aluminum(BAlq), berylliumbis(benzoquinolin-10-olate (Bebq2),9,10-di(naphthalene-2-yl)anthracene (ADN), or a mixture thereof, withoutlimitation. The thickness of the electron transport layer ETL may befrom about 100 Å to about 1,000 Å, for example, from about 150 Å toabout 500 Å. If the thickness of the electron transport layer ETLsatisfies the above-described range, satisfactory electron transportproperties may be obtained without substantial increase of a drivingvoltage.

If the electron transport region ETR includes the electron injectionlayer EIL, the electron transport region ETR may include LiF, lithiumquinolate (LiQ), Li₂O, BaO, NaCl, CsF, a metal in lanthanoides such asYb, or a metal halide such as RbCl and RbI, without limitation. Theelectron injection layer EIL also may be formed using a mixture materialof an electron transport material and an insulating organo metal salt.The organo metal salt may be a material having an energy band gap ofabout 4 eV or more. Particularly, the organo metal salt may include, forexample, a metal acetate, a metal benzoate, a metal acetoacetate, ametal acetylacetonate, or a metal stearate. The thickness of theelectron injection layer EIL may be from about 1 Å to about 100 Å, andfrom about 3 Å to about 90 Å. If the thickness of the electron injectionlayer EIL satisfies the above described range, satisfactory electroninjection properties may be obtained without inducing substantialincrease of a driving voltage.

The electron transport region ETR may include a hole blocking layer, asdescribed above. The hole blocking layer may include, for example, atleast one of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), or4,7-diphenyl-1,10-phenanthroline (Bphen), without limitation.

The second electrode EL2 is provided on the electron transport regionETR. The second electrode EL2 may be a common electrode or a cathode.The second electrode EL2 may be a transmissive electrode, atransflective electrode or a reflective electrode. If the secondelectrode EL2 is the transmissive electrode, the second electrode EL2may include a transparent metal oxide, for example, ITO, IZO, ZnO, ITZO,etc.

If the second electrode EL2 is the transflective electrode or thereflective electrode, the second electrode EL2 may include Ag, Mg, Cu,Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca, LiF/Al, Mo, Ti, acompound including thereof, or a mixture thereof (for example, a mixtureof Ag and Mg). The second electrode EL2 may have a multilayeredstructure including a reflective layer or a transflective layer formedusing the above-described materials and a transparent conductive layerformed using ITO, IZO, ZnO, ITZO, etc.

Even though not shown, the second electrode EL2 may be connected with anauxiliary electrode. If the second electrode EL2 is connected with theauxiliary electrode, the resistance of the second electrode EL2 may bedecreased.

In the organic electroluminescent device 10, voltages are applied toeach of the first electrode EL1 and the second electrode EL2, and holesinjected from the first electrode EL1 move via the hole transport regionHTR to the emission layer EML, and electrons injected from the secondelectrode EL2 move via the electron transport region ETR to the emissionlayer EML. The electrons and the holes are recombined in the emissionlayer EML to generate excitons, and the excitons may emit light viatransition from an excited state to a ground state.

If the organic electroluminescent device 10 is a top emission type, thefirst electrode EL1 may be a reflective electrode, and the secondelectrode EL2 may be a transmissive electrode or a transflectiveelectrode. If the organic electroluminescent device 10 is a bottomemission type, the first electrode EL1 may be the transmissive electrodeor the transflective electrode, and the second electrode EL2 may be thereflective electrode.

The organic electroluminescent device 10 according to an exemplaryembodiment of the inventive concept is characterized in emittingnear-infrared rays, and has effects of high efficiency, etc.

Referring to FIGS. 3 to 9, an organic electroluminescent display deviceaccording an exemplary embodiment of the inventive concept will beexplained. The explanation will be mainly with the difference from theabove-explanation on the organic electroluminescent device according toan exemplary embodiment of the inventive concept, and unexplained partwill follow the above-description.

FIG. 3 is a perspective view of an organic electroluminescent displaydevice according to an exemplary embodiment of the inventive concept.

Referring to FIG. 3, an organic electroluminescent display device DDaccording to an exemplary embodiment of the inventive concept includes aplurality of pixels. FIG. 3 illustrates four kinds of pixels, andparticularly, illustrates a case including a first pixel PX1, a secondpixel PX2, a third pixel PX3 and a fourth pixel PX4. Four kinds of thepixels PX1, PX2, PX3 and PX4 may produce lights in different wavelengthregions, respectively.

For example, the four kinds of pixels PX1, PX2, PX3 and PX4 may bearranged in a matrix shape on a plane defined by an axis in a firstdirection DR1 and an axis in a second direction DR2. In addition, eachof the four kinds of pixels PX1, PX2, PX3 and PX4 may be arranged whilemaking a row in the second direction DR2. However, exemplary embodimentsof the inventive concepts are not limited thereto. The arrangement of aplurality of the pixels may be diversely modified according toembodiment methods of a display panel. In addition, each of the pixelsPX1, PX2, PX3 and PX4 which generate lights in different wavelengthregions is defined as a sub-pixel, and the combination of suchsub-pixels may be defined as a pixel (PX of FIG. 4).

Each of the four kinds of pixels PX1, PX2, PX3 and PX4 includes anorganic electroluminescent device including an emission layer emittinglight in a different wavelength region from each other. This will bedescribed later.

FIG. 4 is a circuit diagram of a pixel among pixels included in anorganic electroluminescent display device according to an exemplaryembodiment of the inventive concept. FIG. 5 is a plan view showing apixel among pixels included in an organic electroluminescent displaydevice according to an exemplary embodiment of the inventive concept.FIG. 6 is a cross-sectional view taken along a region II-II′ of FIG. 5.

Referring to FIGS. 4 to 6, a pixel PX may be connected with a wire partincluding a gate line GL, a data line DL and a driving voltage line DVL.The pixel PX includes thin film transistors TFT1 and TFT2 connected tothe wire part, and an organic electroluminescent device OEL connected tothe thin film transistors TFT1 and TFT2, and a capacitor Cst.

The gate line GL is extended in a first direction DR1. The data line DLis extended in a second direction DR2 which crosses the gate line GL.The driving voltage line DVL is extended in substantially the samedirection as the data line DL, that is, in the second direction DR2. Thegate line GL delivers scanning signals to the thin film transistors TFT1and TFT2, the data line DL delivers data signals to the thin filmtransistors TFT1 and TFT2, and the driving voltage line DVL provides thethin film transistors TFT1 and TFT2 with a driving voltage.

The thin film transistors TFT1 and TFT2 may include a driving thin filmtransistor TFT2 for controlling the organic electroluminescent deviceOEL and a switching thin film transistor TFT1 for switching the drivingthin film transistor TFT2. In an exemplary embodiment of the inventiveconcept, a case where a pixel PX includes two thin film transistors TFT1and TFT2 is explained. However, exemplary embodiments of the inventiveconcepts are not limited thereto. The pixel PX may include one thin filmtransistor and one capacitor, or the pixel PX may be provided with atleast three thin film transistors and at least two capacitors.

The switching thin film transistor TFT1 includes a first gate electrodeGE1, a first source electrode SE1 and a first drain electrode DE1. Thefirst gate electrode GE1 is connected with the gate line GL, and thefirst source electrode SE1 is connected with the data line DL. The firstdrain electrode DE1 is connected with a first common electrode CE1 by afifth contact hole CH5. The switching thin film transistor TFT1 deliversdata signals applied to the data line DL to the driving thin filmtransistor TFT2 according to scanning signals applied to the gate lineGL.

The driving thin film transistor TFT2 includes a second gate electrodeGE2, a second source electrode SE2 and a second drain electrode DE2. Thesecond gate electrode GE2 is connected with the first common electrodeCE1. The second source electrode SE2 is connected with the drivingvoltage line DVL. The second drain electrode DE2 is connected with thefirst electrode EL1 by a third contact hole CH3.

The capacitor Cst is connected between the second gate electrode GE2 andthe second source electrode SE2 of the driving thin film transistor TFT2and charges and maintains data signals inputted to the second gateelectrode GE2 of the driving thin film transistor TFT2. The capacitorCst may include a first common electrode CE1 which is connected with thefirst drain electrode DE1 by a sixth contact hole CH6 and a secondcommon electrode CE2 which is connected with the driving voltage lineDVL.

The organic electroluminescent display device (DD of FIG. 3) accordingto an exemplary embodiment of the inventive concept may include a basesubstrate BS on which thin film transistors TFT1 and TFT2 and an organicelectroluminescent device OEL are laminated. The base substrate BS maybe formed using any material commonly used without specific limitation,and may be formed using an insulating material, for example, glass,plastics, quartz, etc. Organic polymers forming the base substrate BSmay include polyethylene terephthalate (PET), polyethylene naphthalate(PEN), polyimide, polyether sulfone, etc. The base substrate BS may beselected in consideration of mechanical strength, thermal stability,transparency, surface smoothness, availability of handling, waterresistance, etc.

On the base substrate BS, a substrate buffer layer (not shown) may bedisposed. The substrate buffer layer (not shown) may prevent thediffusion of impurities into the switching thin film transistor TFT1 andthe driving thin film transistor TFT2. The substrate buffer layer (notshown) may be formed using silicon nitride (SiNx), silicon oxide (SiOx),silicon oxynitride (SiOxNy), etc., and may be omitted according to thematerial of the base substrate BS and process conditions.

On the base substrate BS, a first semiconductor layer SM1 and a secondsemiconductor layer SM2 are disposed. The first semiconductor layer SM1and the second semiconductor layer SM2 are formed using a semiconductormaterial, and are operated as active layers of the switching thin filmtransistor TFT1 and the driving thin film transistor TFT2, respectively.Each of the first semiconductor layer SM1 and the second semiconductorlayer SM2 includes a source area SA, a drain area DRA and a channel areaCA disposed between the source area SA and the drain area DRA. Each ofthe first semiconductor layer SM1 and the second semiconductor layer SM2may be selected and formed from an inorganic semiconductor or an organicsemiconductor. The source area SA and the drain area DRA may be dopedwith n-type impurities or p-type impurities.

On the first semiconductor layer SM1 and the second semiconductor layerSM2, a gate insulating layer GI is disposed. The gate insulating layerGI covers the first semiconductor layer SM1 and the second semiconductorlayer SM2. The gate insulating layer GI may be formed using an organicinsulating material or an inorganic insulating material.

On the gate insulating layer GI, a first gate electrode GE1 and a secondgate electrode GE2 are disposed. Each of the first gate electrode GE1and the second gate electrode GE2 is formed to cover the areacorresponding to the channel area CA of each of the first semiconductorlayer SM1 and the second semiconductor layer SM2.

On the first gate electrode GE1 and the second gate electrode GE2, aninsulating interlayer IL is disposed. The insulating interlayer ILcovers the first gate electrode GE1 and the second gate electrode GE2.The insulating interlayer IL may be formed using an organic insulatingmaterial or an inorganic insulating material.

On the insulating interlayer IL, a first source electrode SE1, a firstdrain electrode DE1, a second source electrode SE2 and a second drainelectrode DE2 are disposed. The second drain electrode DE2 makes contactwith a drain area DRA of a second semiconductor layer SM2 by a firstcontact hole CH1 which is formed in the gate insulating layer GI and theinsulating interlayer IL, and the second source electrode SE2 makescontact with a source area SA of the second semiconductor layer SM2 by asecond contact hole CH2 which is formed in the gate insulating layer GIand the insulating interlayer IL. The first source electrode SE1 makescontact with a source area (not shown) of the first semiconductor layerSM1 by a fourth contact hole CH4 which is formed in the gate insulatinglayer GI and the insulating interlayer IL, and the first drain electrodeDE1 makes contact with a drain area (not shown) of the firstsemiconductor layer SM1 by a fifth contact hole CH5 which is formed inthe gate insulating layer GI and the insulating interlayer IL.

On the first source electrode SE1, the first drain electrode DE1, thesecond source electrode SE2, and the second drain electrode DE2, apassivation layer PL is disposed. The passivation layer PL may act as aprotection layer protecting the switching thin film transistor TFT1 andthe driving thin film transistor TFT2, or act as a planarization layerplanarizing the top surface thereof.

On the passivation layer PL, an organic electroluminescent device OEL isdisposed. The organic electroluminescent device OEL includes a firstelectrode EL1, a second electrode EL2 disposed on the first electrodeEL1, and an organic layer OL including an emission layer EML which isdisposed between the first electrode EL1 and the second electrode EL2.

Particularly, on the passivation layer PL, the first electrode EL1 isprovided, and on the passivation layer PL and the first electrode EL1, apixel defining layer PDL is provided. In the pixel defining layer PDL,an opening part OH exposing at least a portion of the top surface of thefirst electrode EL1 is defined. The pixel defining layer PDL maypartition the organic electroluminescent device OEL so as to correspondto each of the pixels PX.

The pixel defining layer PDL may be formed using a polymer resin. Forexample, the pixel defining layer PDL may be formed by including apolyacrylate-based resin or a polyimide-based resin. In addition, thepixel defining layer PDL may be formed by further including an inorganicmaterial in addition to the polymer resin. Meanwhile, the pixel defininglayer PDL may be formed by including a light absorbing material, or maybe formed by including a black pigment or a black dye. The pixeldefining layer PDL formed by including the black pigment or the blackdye may accomplish a black pixel defining layer. During forming thepixel defining layer PDL, carbon black may be used as the black pigmentor the black dye, but exemplary embodiments of the inventive conceptsare not limited thereto.

In addition, the pixel defining layer PDL may be formed using aninorganic material. For example, the pixel defining layer PDL may beformed by including silicon nitride (SiN_(x)), silicon oxide (SiO_(x)),silicon oxynitride (SiO_(x)N_(y)), etc.

On the pixel defining layer PDL and the first electrode EL1, an organiclayer OL and a second electrode EL2 are laminated one by one. Theorganic layer OL includes a hole transport region HTR, an emission layerEML, and an electron transport region ETR. Explanation on the firstelectrode EL1, the hole transport region HTR, the electron transportregion ETR and the second electrode EL2 is the same as described above,and will be omitted.

FIG. 7 is a cross-sectional view taken along a region I-I′ of FIG. 3.

Referring to FIG. 7, an organic electroluminescent display device DD ofthe inventive concept may include a plurality of pixel areas PXA-1,PXA-2, PXA-3 and PXA-4. For example, a first pixel area PXA-1, a secondpixel area PXA-2, a third pixel area PXA-3 and a fourth pixel areaPXA-4, which emit lights in different wavelength regions, may beincluded. In an exemplary embodiment shown in FIG. 7, the first pixelarea PXA-1 may be a blue pixel area, the second pixel area PXA-2 may bea green pixel area, the third pixel area PXA-3 may be a red pixel area,and the fourth pixel area PXA-4 may be a near-infrared pixel area. Thatis, in an exemplary embodiment, the organic electroluminescent displaydevice DD may include a blue pixel area, a green pixel area, a red pixelarea, and a near-infrared pixel area. For example, the blue pixel areais a blue light-emitting area which emits blue light, the green pixelarea and the red pixel area represent a green light-emitting area and ared light-emitting area, respectively, and the near-infrared pixel areais an area emitting near-infrared rays in a wavelength region of about750 nm to about 1,000 nm. Meanwhile, the pixel areas PXA-1, PXA-2, PXA-3and PXA-4 may be light-emitting areas corresponding to the plurality ofpixels PX1, PX2, PX3 and PX4, respectively, in the explanation referringto FIG. 3.

The first pixel area PXA-1 may be an area in which a first organicelectroluminescent device OEL1 having a first organic layer OL1 whichemits first visible rays is disposed. The second pixel area PXA-2 andthe third pixel area PXA-3 may be areas in which a second organicelectroluminescent device OEL2 which emits second visible rays and athird organic electroluminescent device OEL3 which emits third visiblerays are disposed, respectively. The fourth pixel area PX-4 may be anarea in which a fourth organic electroluminescent device OEL4 whichemits near-infrared rays is disposed. The first visible rays, the secondvisible rays and the third visible rays may have different wavelengthregions. However, exemplary embodiments of the inventive concepts arenot limited thereto. They may have the same wavelength region, or two ofthe first visible rays, the second visible rays and the third visiblerays may have the same wavelength region and the remaining one may havea different wavelength region.

The first pixel area PXA-1, the second pixel area PXA-2 and the thirdpixel area PXA-3 may be areas in which pixels achieving images aredisposed, and the fourth pixel area PXA-4 may be an area in which apixel other than the pixels achieving images, is disposed.

For example, the first organic electroluminescent device OEL1 mayinclude a first electrode EL11, a first organic layer OL1 and a secondelectrode EL21. Meanwhile, even though not shown, the first organiclayer OL1 may include a hole transport region, an emission layer and anelectron transport region. For example, the first organic layer OL1 mayinclude an emission layer emitting blue light, and a luminescentmaterial may be selected from materials known as blue light-emittingmaterials, without limitation. The second organic electroluminescentdevice OEL2 may include a first electrode EL12, a second organic layerOL2 and a second electrode EL22, and the third organicelectroluminescent device OEL3 may include a first electrode EL13, athird organic layer OL3 and a second electrode EL23. The second organiclayer OL2 and the third organic layer OL3 may include emission layersemitting green light and red light, respectively, and luminescentmaterials may be selected from materials known as green light-emittingmaterials and red light-emitting materials, without limitation.

Meanwhile, the fourth organic electroluminescent device OEL4 maycorrespond to the organic electroluminescent device (for example, 10 ofFIG. 1) according to an exemplary embodiment of the inventive concept.Particularly, the fourth organic electroluminescent device OEL4 mayinclude an emission layer emitting near-infrared rays. The fourthorganic electroluminescent device OEL4 includes a first electrode EL14,a fourth organic layer OL4 and a second electrode EL24, and the fourthorganic layer OL4 may include an emission layer emitting near-infraredrays.

Referring to FIG. 3 again, each of the first pixel PX1, the second pixelPX2, the third pixel PX3 and the fourth pixel PX4 may be provided inplural.

FIG. 3 illustrates the first pixel PX1, the second pixel PX2, the thirdpixel PX3 and the fourth pixel PX4 arranged in the first direction.However, exemplary embodiments of the inventive concepts are not limitedthereto. In addition, FIG. 3 illustrates the first pixel PX1, the secondpixel PX2, the third pixel PX3 and the fourth pixel PX4 having the samesize. However, exemplary embodiments of the inventive concepts are notlimited thereto.

FIG. 8 is a plan view illustrating the relation of a pixel layout of anorganic electroluminescent display device according to an exemplaryembodiment of the inventive concept. FIG. 9 is a plan view illustratingthe relation of a pixel layout of an organic electroluminescent displaydevice according to an exemplary embodiment of the inventive concept.

Referring to FIGS. 8 and 9, at least one of a first pixel PX1, a secondpixel PX2, a third pixel PX3 or a fourth pixel PX4 may have a differentsize. In addition, at least one of the first pixel PX1, the second pixelPX2, the third pixel PX3 or the fourth pixel PX4 may be extended in adifferent direction or may be arranged in a different direction.

The organic electroluminescent display device according to an exemplaryembodiment of the inventive concept includes a pixel emittingnear-infrared rays in a display area, and the pixel may be utilized as apixel achieving sensing function using near-infrared rays. Accordingly,a configuration of sensing function such as fingerprint recognition andiris recognition may be disposed in a display area, thereby decreasingthe dimension of a non-display area.

Hereinafter, the organometallic compound according to an exemplaryembodiment of the inventive concept will be explained.

The organometallic compound according to an exemplary embodiment of theinventive concept may be used as a material for an emission layer in theorganic electroluminescent device according to an exemplary embodimentof the inventive concept. In addition, the organometallic compoundaccording to an exemplary embodiment of the inventive concept may beused as a material for an emission layer in a fourth organicelectroluminescent device included in the above-described organicelectroluminescent display device according to an exemplary embodimentof the inventive concept.

In the present disclosure, ———means a part to be connected, for example,a coordination bond.

In the present disclosure, “substituted or unsubstituted” may meansubstituted with at least one substituent selected from the groupconsisting of a deuterium atom, an alkyl group, an alkenyl group, aheterocycle, and an aryl group, or unsubstituted. In addition, each ofthe substituents illustrated above may be substituted or unsubstituted.For example, a biphenyl group may be interpreted as an aryl group, or aphenyl group substituted with a phenyl group.

In the present disclosure, “combining each other to form a ring” maymean combining each other to form a substituted or unsubstitutedhydrocarbon ring, or a substituted or unsubstituted heterocycle. Inaddition, a ring formed by the combination with an adjacent group may beconnected with other ring to form a spiro structure.

In the present disclosure, the hydrocarbon ring may include an aliphatichydrocarbon ring and an aromatic hydrocarbon ring (aryl group). Aheterocycle includes an aliphatic heterocycle and an aromaticheterocycle (heteroaryl group). The hydrocarbon ring and the heterocyclemay be a monocycle or polycycle.

In the present disclosure, “adjacent group” may mean a substituentsubstituted for an atom which is directly bonded to an atom for which acorresponding substituent is substituted, another substituent which issubstituted for an atom for which a corresponding substituent issubstituted, or a substituent which is sterically the closest to acorresponding substituent. For example, two methyl groups in1,2-dimethylbenzene may be interpreted as “adjacent groups” to eachother, and two ethyl groups in 1,1-diethylcyclopentene may beinterpreted as “adjacent groups” to each other.

In the present disclosure, alkyl may have a linear or branched chain ora cycle shape. The carbon number of the alkyl may be 1 to 30, 1 to 20, 1to 10, or 1 to 6. Examples of the alkyl may include methyl, ethyl,n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, i-butyl, 2-ethylbutyl,3,3-dimethylbutyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, cyclopentyl,1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl,n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, cyclohexyl,4-methylcyclohexyl, 4-t-butylcyclohexyl, n-heptyl, 1-methylheptyl,2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, t-octyl,2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl, cyclooctyl,n-nonyl, n-decyl, adamantyl, 2-ethyldecyl, 2-butyldecyl, 2-hexyldecyl,2-octyldecyl, n-undecyl, n-dodecyl, 2-ethyldodecyl, 2-butyldodecyl,2-hexyldodecyl, 2-octyldodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl,n-hexadecyl, 2-ethylhexadecyl, 2-butylhexadecyl, 2-hexylhexadecyl,2-octylhexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl,2-ethyl eicosyl, 2-butyl eicosyl, 2-hexyl eicosyl, 2-octyl eicosyl,n-henicosyl, n-docosyl, n-tricosyl, n-tetracosyl, n-pentacosyl,n-hexacosyl, n-heptacosyl, n-octacosyl, n-nonacosyl, n-triacontyl, etc.,without limitation.

In the present disclosure, alkenyl may be linear or branched. The carbonnumber of the alkenyl is not specifically limited, and may be 2 to 30, 2to 20, or 2 to 10. Examples of the alkenyl may include vinyl, 1-butenyl,1-pentenyl, 1,3-butadienyl aryl, styrenyl, styrylvinyl, etc., withoutlimitation.

In the present disclosure, aryl means an optional functional group orsubstituent derived from an aromatic hydrocarbon ring. The aryl may bemonocyclic aryl or polycyclic aryl. The carbon number of the aryl forforming a ring may be 6 to 60, 6 to 30, 6 to 20, or 6 to 15. Examples ofthe aryl may include phenyl, naphthyl, fluorenyl, anthracenyl,phenanthryl, biphenyl, terphenyl, quaterphenyl, quinqphenyl, sexiphenyl,biphenylene, triphenylene, pyrenyl, benzofluoranthenyl, chrysenyl, etc.,without limitation.

In the present disclosure, fluorenyl may be substituted, or twosubstituents may be combined with each other to form a spiro structure.Examples of the substituted fluorenyl are as follows. However, exemplaryembodiments of the inventive concepts are not limited thereto.

In the present disclosure, heteroaryl may be heteroaryl including atleast one of O, N, P, Si or S as a heteroatom. If the heteroarylincludes two heteroatoms, two heteroatoms may be the same or differentfrom each other. The carbon number of the heteroaryl for forming a ringmay be 2 to 30 or 2 to 20. The heteroaryl may be monocyclic heteroarylor polycyclic heteroaryl. The polycyclic heteroaryl may have a structureof, for example, two rings or three rings. Examples of the heteroarylmay include thiophene, furan, pyrrole, imidazole, thiazole, oxazole,oxadiazole, triazole, pyridine, bipyridine, pyrimidine, triazine,triazole, acridyl, pyridazine, pyrazinyl, quinoline, quinazoline,quinoxaline, phenoxazine, phthalazine, pyrido pyrimidine, pyridopyrazine, pyrazino pyrazine, isoquinoline, indole, carbazole,N-arylcarbazole, N-heteroaryl carbazole, N-alkyl carbazole, benzoxazole,benzoimidazole, benzothiazole, benzocarbazole, benzothiophene,dibenzothiophene, thienothiophene, benzofuran, phenanthroline, thiazole,isooxazole, oxadiazole, thiadiazole, phenothiazine, dibenzosilole,dibenzofuran, etc., without limitation.

In the present disclosure, a direct linkage may include a single bond.

The organometallic compound according to an exemplary embodiment of theinventive concept is represented by the following Formula 1:

In Formula 1, R₁ and R₂ are each independently a hydrogen atom, adeuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted aryl group having 6 to30 carbon atoms for forming a ring, or a substituted or unsubstitutedheteroaryl group having 2 to 30 carbon atoms for forming a ring, or maybe combined with an adjacent group to form a ring, “p” is an integer of0 to 4, “q” is an integer of 0 to 3, “n” is 1 or 2, M is Pt, Ir or Os,and L₁ is a bidentate ligand (divalent organic ligand).

If “p” is 2 or more, a plurality of R₁ groups are the same or different,and if “q” is 2 or more, a plurality of R₂ groups are the same ordifferent. If “p” is 1, R₁ may be a substituent other than a hydrogenatom, and if “q” is 1, R₂ may be a substituent other than a hydrogenatom.

As described above, if R₁ and/or R₂ are in plural, they may be combinedwith an adjacent group to form a ring. In this case, Formula 1 may bemore conjugated, and long wavelength may be emitted.

Formula 1 may be represented by one of Formulae 1-1 to 1-3 below.However, Formulae 1-1 to 1-3 are only illustrations, and an exemplaryembodiment of the inventive concept is not limited thereto.

In Formulae 1-1 to 1-3, M, L₁, R₂, “n” and “q” are the same as describedabove.

In Formulae 1-1 to 1-3, a naphthalene ring may be substituted with oneor more substituents.

L₁ is not specifically limited only if a bidentate ligand (divalentorganic ligand), and may be, for example, represented by one of thefollowing Formulae 2-1 to 2-6:

In Formula 2-1, X₁ is O or NR′, R₃ to R₅ are each independently ahydrogen atom, a deuterium atom, a substituted or unsubstituted alkylgroup having 1 to 10 carbon atoms, or a substituted or unsubstitutedaryl group having 6 to 30 carbon atoms for forming a ring, or may becombined with an adjacent group to form a ring.

In Formula 2-2, R₆ to R₉ are each independently a hydrogen atom, adeuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, or a substituted or unsubstituted aryl group having 6to 30 carbon atoms for forming a ring, or may be combined with anadjacent group to form a ring, “a” is an integer of 0 to 4, and “b” isan integer of 0 to 5.

In Formula 2-2, if “a” is 2 or more, a plurality of R₈ groups are thesame or different, and if “b” is 2 or more, a plurality of R₉ groups arethe same or different. In Formula 2-2, if “a” is 1, R₈ group may be asubstituent other than a hydrogen atom, and if “q” is 1, R₉ may be asubstituent other than a hydrogen atom.

In Formula 2-3, R₁₀ and R₁₁ are each independently a hydrogen atom, adeuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, or a substituted or unsubstituted aryl group having 6to 30 carbon atoms for forming a ring, or may be combined with anadjacent group to form a ring, and “c” and “d” are each independently aninteger of 0 to 4.

In Formula 2-3, if “c” is 2 or more, a plurality of R₁₀ groups are thesame or different, and if “d” is 2 or more, a plurality of R₁₁ groupsare the same or different. In Formula 2-3, if “c” is 1, R₁₀ may be asubstituent other than a hydrogen atom, and if “d” is 1, R₁₁ may be asubstituent other than a hydrogen atom.

In Formula 2-4, R₁₂ to R₁₅ are each independently a hydrogen atom, adeuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, or a substituted or unsubstituted aryl group having 6to 30 carbon atoms for forming a ring, or may be combined with anadjacent group to form a ring, and “e” is an integer of 0 to 4.

In Formula 2-4, if “e” is 2 or more, a plurality of R₁₅ groups are thesame or different, and if “e” is 1, R₁₅ may be a substituent other thana hydrogen atom.

In Formulae 2-5, R₁₆ and R₁₇ are each independently a hydrogen atom, adeuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, or a substituted or unsubstituted aryl group having 6to 30 carbon atoms for forming a ring, or may be combined with anadjacent group to form a ring, “f” is an integer of 0 to 3, and “g” isan integer of 0 to 4.

In Formula 2-5, if “f” is 2 or more, a plurality of R₁₆ groups are thesame or different, and if “g” is 2 or more, a plurality of R₁₇ groupsare the same or different. In Formula 2-5, if “f” is 1, R₁₆ may be asubstituent other than a hydrogen atom, and if “g” is 1, R₁₇ may be asubstituent other than a hydrogen atom.

In Formula 2-6, X₂ to X₄ are each independently CH, N, or NR₂₁, Y₁ is adirect linkage or CH, R₁₈ to R₂₁ are each independently a hydrogen atom,a deuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, or a substituted or unsubstituted aryl group having 6to 30 carbon atoms for forming a ring, or may be combined with anadjacent group to form a ring, “h” is an integer of 0 to 2, “i” is aninteger of 0 to 3, and “j” is an integer of 0 to 4.

In Formula 2-6, if Y₁ is a direct linkage, a ring including X₂ and X₃ isa five-member ring.

In Formulae 2-6, if “h” is 2 or more, a plurality of R₁₈ groups are thesame or different, if “i” is 2 or more, a plurality of R₁₉ groups arethe same or different, if “j” is 2 or more, a plurality of R₂₀ groupsare the same or different. In Formula 2-6, if “h” is 1, R₁₈ may be asubstituent other than a hydrogen atom, if “i” is 1, R₁₉ may be asubstituent other than a hydrogen atom, and if “j” is 1, R₂₀ may be asubstituent other than a hydrogen atom.

Formula 2-1 may be, for example, represented by one of the followingFormulae 3-1 to 3-3:

In Formulae 3-2 and 3-3, the benzene ring may be substituted with one ormore substituents.

An exemplary embodiment of the inventive concept is not limited thereto,but L₁ is preferably represented by one of Formulae 3-1 to 3-3.

Formula 2-2 may be, for example, represented by one of Formulae 2-2-1 to2-2-3. However, exemplary embodiments of the inventive concepts are notlimited thereto.

In Formulae 2-2-1 to 2-2-3, R₆ to R₉, “a” and “b” are the same asdescribed above.

In Formulae 2-2-2 and 2-2-3, the benzene ring of a benzoimidazole may besubstituted with one or more substituents.

Formula 2-3 may be, for example, represented by one of Formulae 2-3-1 to2-3-4. However, exemplary embodiments of the inventive concepts are notlimited thereto.

In Formulae 2-3-1 to 2-3-4, X₅ is O, S or NR″, R″ is a hydrogen atom, adeuterium atom, an alkyl group or an aryl group, and R₁₀, R₁₁, “c” and“d” are the same as described above.

In Formulae 2-3-2 to 2-3-4, the benzene ring of isoquinoline may besubstituted with one or more substituents.

Formula 2-4 may be, for example, represented by Formula 2-4-1 or 2-4-2.However, exemplary embodiments of the inventive concepts are not limitedthereto.

In Formulae 2-4-1 and 2-4-2, R₁₂, R₁₃, R₁₅ and “e” are the same asdescribed above.

In Formulae 2-4-1 and 2-4-2, the benzene ring may be substituted withone or more substituents.

Formula 2-5 may be, for example, represented by Formula 2-5-1. However,exemplary embodiments of the inventive concepts are not limited thereto.

The structure represented by Formula 2-5-1 may be substituted with oneor more substituents.

Formula 2-6 may be, for example, represented by one of Formulae 2-6-1 to2-6-3. However, exemplary embodiments of the inventive concepts are notlimited thereto.

In Formulae 2-6-1 to 2-6-3, R₁₈ to R₂₁, “h”, “i” and “j” are the same asdescribed above.

In Formula 2-6-3, the imidazole ring may be substituted with one or moresubstituents.

Exemplary embodiments of the inventive concepts are not limited thereto,but in Formula 1, M is preferably Pt.

In Formula 1, M is Pt, and L₁ may be represented by one of the aboveFormulae 3-1 to 3-3.

In Formula 1, each of “p” and “q” may be 0. Exemplary embodiments of theinventive concepts are not limited thereto, but at least one of “p” or“q” may be 1 or more, and at least one of R₁ or R₂ may be a methylgroup, an ethyl group, a propyl group, a butyl group, a carbazole group,or a phenyl group. For example, at least one of R₁ or R₂ may be at-butyl group, a carbazole group, or a phenyl group.

The organometallic compound represented by Formula 1 according to anexemplary embodiment of the inventive concept may be one selected fromthe compounds represented in Compound Group 1. However, exemplaryembodiments of the inventive concepts are not limited thereto.

The organometallic compound according to an exemplary embodiment of theinventive concept is characterized in including an oxidated thiadiazolestructure, and thus, may be used as a luminescent material ofnear-infrared rays. For example, the organometallic compound accordingto an exemplary embodiment of the inventive concept may be used as aluminescent material emitting near-infrared rays in a wavelength regionof about 750 nm to about 1,000 nm.

Referring to FIGS. 1 and 2 again, the emission layer EML included in theorganic electroluminescent device 10 according to an exemplaryembodiment of the inventive concept will be explained in moreparticularly. The emission layer EML described below corresponds to anemission layer included in the fourth organic electroluminescent deviceOEL4 of the organic electroluminescent display device (DD in FIG. 7)according to an exemplary embodiment of the inventive concept.

The emission layer EML may include one or two or more kinds of theorganometallic compound represented by Formula 1. The emission layer EMLmay further include a known material in addition to the organometalliccompound represented by Formula 1.

The emission layer EML includes a host and a dopant, and the dopant mayinclude the organometallic compound represented by Formula 1 accordingto an exemplary embodiment of the inventive concept. The emission layerEML uses the organometallic compound represented by Formula 1 accordingto an exemplary embodiment of the inventive concept and may be anemission layer emitting near-infrared rays.

Commonly used materials are not specifically limited as the host. Amonga red host, a green host and a blue host, the red host is morepreferable. The host may include at least one of Compound H-1 to H-15,without limitation.

The organometallic compound according to an exemplary embodiment of theinventive concept may be used as a luminescent material of an organicelectroluminescent device and an organic electroluminescent displaydevice, and more particularly, as a luminescent material ofnear-infrared rays. The organic electroluminescent device and theorganic electroluminescent display device including the organometalliccompound according to an exemplary embodiment of the inventive conceptmay favorably accomplish high efficiency.

The organometallic compound represented by Formula 1 may be preparedbased on the synthetic examples described below. However, the syntheticprocess of the organometallic compound represented by Formula 1 is notlimited to the synthetic examples described below, and any reactionconditions known in the art may be applied.

Hereinafter, the inventive concept will be explained more particularlyreferring to preferred embodiments. The following embodiments are onlyfor illustration to assist the understanding of the inventive concept,and the scope of the inventive concept is not limited thereto.

Synthetic Examples

The organometallic compound according to an exemplary embodiment of theinventive concept may be synthesized, for example, as follows. However,the synthetic method of the organometallic compound according toexemplary embodiments of the inventive concepts are not limited thereto.

1. Synthesis of Compound 1

Synthesis of Compound 1-1

Under conditions of about −78° C. and a N₂ gas atmosphere,bis(cyclopentadienyl)titanium(IV) dichloride (Cp₂TiCl₂) (1.2 eq) wasdissolved in THF, and sec-butylmagnesium chloride (sec-BuMgCl) (1.2 eq,2.0 M in ethyl ether) was slowly added thereto. The resultant mixturewas stirred at about −78° C. for about 2 hours and at room temperaturefor about 30 minutes. To the resultant mixture, benzaldehyde (1 eq) wasslowly injected and the reaction was finished. An organic layerextracted with methylene chloride (MC) was dried with Na₂SO₄, andsolvents were removed. The crude product thus obtained was separated bycolumn chromatography to obtain Compound 1-1 (yield: 86%). ¹H NMR(CDCl₃, 600 MHz): 7.71-7.70 (2H, d), 7.68-7.67 (2H, d), 7.40-7.39 (2H,t), 7.37-7.34 (2H, t), 7.29-7.26 (2H, t), 5.78 (2H, s), 2.99 (2H, s).

Synthesis of Compound 1-2

Compound 1-1 (1 eq) and N-bromosuccinimide (2 eq) were dissolved inCCl₄. The resultant mixture was stirred and refluxed for about 5 hoursand the mixture thus obtained was filtered and washed with an ethylether solvent. The solid compound thus obtained was extracted with MC,an organic layer was dried with Na₂SO₄, and solvents were removed. Thecrude product thus obtained was separated by column chromatography toobtain Compound 1-2 (yield: 52%). ¹H NMR (CDCl₃, 600 MHz): δ 9.36-9.35(2H, d), 8.04-8.02 (2H, d), 7.77-7.75 (2H, t), 7.66-7.63 (2H, t),7.51-7.48 (2H, t).

Synthesis of Compound 1-3

Compound 1-2 (1 eq) and sulfamide (4.5 eq) were dissolved in ananhydrous ethanol solvent and stirred and refluxed for about 8 hourswhile passing HCl gas through the reaction mixture. After finishing thereaction, the resultant reaction product was extracted with MC, anorganic layer was dried with Na₂SO₄, and solvents were removed. Thecrude product thus obtained was separated by column chromatography toobtain Compound 1-3 (yield: 39%). ¹H NMR (CDCl₃, 600 MHz): δ 8.30-8.28(2H, m), 8.00-7.98 (2H, d), 7.92-7.90 (2H, m), 7.24-7.15 (4H, m).

Synthesis of Compound 1-4

Under a nitrogen atmosphere, a solution in which Compound 1-3 (1 eq) wasdissolved was maintained at about 0° C., and anhydrous aluminum chloride(4 eq) was injected thereto. The resultant mixture was stirred at roomtemperature for about 1 hour and washed with cold ice water, and then,was filtered. The solid thus obtained was completely dried in adesiccator to obtain Compound 1-4 (42%). ¹H NMR (CDCl₃, 600 MHz): δ8.00-7.98 (2H, d), 7.85-7.82 (2H, d), 7.24-7.15 (4H, m).

Synthesis of Compound 1

Compound 1-4 (2 eq) and K₂PtCl₄ (1 eq) were dissolved in a solvent of2-ethoxyethanol:water (3:1), and stirred at about 80° C. for about 16hours. To the resultant mixture, Na₂CO₂ (10 eq) dissolved in2-ethoxyethanol and acetylacetone (3 eq) were injected, and stirred atabout 100° C. for about 16 hours. The resultant reaction product waswashed with ice water, filtered, separated by column chromatography andrecrystallized to obtain Compound 1 (yield: 30%). High resolution EI-MS(M+) for C₁₄H₈N₂S was as follows: found: 561.45; calc.: 561.48.

2. Synthesis of Compound 2

Synthesis of Compound 2-1

Under a nitrogen atmosphere, Compound 1-4 (1 eq) was dissolved in a THFsolvent. In a lightless state at about 0° C., N-bromosuccinimide (2.2eq) dissolved in a small amount of THF was slowly injected to thereaction mixture, followed by stirring at room temperature for about 8hours. After finishing the reaction, the reaction mixture was extractedwith a MC solvent, an organic layer was dried with Na₂SO₄, and solventswere removed. The crude product was separated by column chromatographyto obtain Compound 2-1 (yield: 52%). ¹H NMR (CDCl₃, 600 MHz): δ 8.50(2H, s), 8.00-7.96 (4H, m).

Synthesis of Compound 2-2

Under a nitrogen atmosphere, Compound 1-4 (1 eq), phenylboronic acid(1.2 eq), K₂CO₃ (2 eq) and 5% Pd(PPh₃)₄ were stirred and refluxed in atoluene solvent for about 18 hours. After finishing the reaction, theresultant reaction mixture was extracted with an MC solvent, an organiclayer was dried with Na₂SO₄, and solvents were removed. The crudeproduct was separated by column chromatography to obtain Compound 2-2(yield: 47%). ¹H NMR (CDCl₃, 600 MHz): δ 8.60 (2H, s), δ 8.50 (4H, d),8.30-8.28 (4H, d), 8.10-8.08 (4H, d), 8.00-7.96 (2H, m).

Synthesis of Compound 2

Compound 2-2 (2 eq) and K₂PtCl₄ (1 eq) were dissolved in a solvent of2-ethoxyethanol:water (3:1), and stirred at about 80° C. for about 16hours. To the resultant mixture, Na₂CO₂ (10 eq) dissolved in2-ethoxyethanol and acetylacetone (3 eq) were injected, and stirred atabout 100° C. for about 16 hours. The resultant reaction product waswashed with ice water, filtered, separated by column chromatography andrecrystallized to obtain Compound 2 (yield: 25%). High resolution EI-MS(M+) for C₁₄H₈N₂S was as follows: found: 713.65; calc.: 713.67.

The above-described synthetic examples are only illustrations, and thereaction conditions may be changed according to need. In addition, thecompound according to an exemplary embodiment of the inventive conceptmay be synthesized so as to include various substituents using methodsand materials known in the art. By introducing various substituents in acore structure represented by Formula 1, appropriate properties for anorganic electroluminescent device may be attained.

Device Manufacturing Examples

An organic electroluminescent device of Example 1 was manufactured usingCompound 1 as a dopant material in an emission layer.

Example Compound

An organic electroluminescent device of Comparative Example 1 wasmanufactured using a known material, i.e., platinum phthalocyanine(PtPc) as a dopant material of an emission layer.

The organic electroluminescent devices of Example 1 and ComparativeExample 1 were manufactured as follows. On a glass substrate, an ITOlayer with a thickness of about 1200 Å was formed. Then, ultrasoniccleaning and pre-treatment (UV/O₃, heat treatment) were performed. Onthe pre-treated ITO transparent electrode, i) a hole injection layer(p-doping 1%, about 100 Å), ii) a hole transport layer (about 1100 Å),iii) an emission layer (host+dopant 1%, about 300 Å), iv) an electrontransport layer (ET1+ET2, about 300 Å), v) an electron injection layer(LiF, about 5 Å), and vi) a second electrode (Al, about 1500 Å) werelaminated one by one.

The materials of the electron injection/transport layer, the emissionlayer (host), and the electron transport layer are as follows.

(Hole Injection Layer Material)

(Hole Transport Layer Material)

(Emission Layer Host)

(Electron Transport Layer Material)

Then, the driving voltage, external quantum efficiency (EQE), andmaximum emission wavelength of the organic electroluminescent devicesthus manufactured were measured. Evaluation results are listed in Table2 below. The driving voltage, EQE, etc. are measured values at a currentdensity of about 100 mA/cm².

TABLE 1 Maximum Driving External quantum emission Emission layer voltageefficiency (EQE, wavelength dopant material (V) %) λmax Example 1Compound 1 6.4 1.03 826 Comparative PtPc 7.0 0.31 962 Example 1

Referring to Table 1, it may be found that Example 1 had decreaseddriving voltage and increased efficiency when compared to ComparativeExample 1. The organometallic compound according to an exemplaryembodiment of the inventive concept emits near-infrared rays (NIR) andhas more favorable efficiency and driving life in contrast to PtPc whichis a known NIR emitting material.

The organic electroluminescent device according to an exemplaryembodiment of the inventive concept and the organic electroluminescentdisplay device including the same are capable of emitting near-infraredrays with high efficiency.

The organometallic compound according to an exemplary embodiment of theinventive concept may be used as a luminescent material of near-infraredrays, and if used in an organic electroluminescent device, theorganometallic compound may contribute to the increase of efficiency.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather to the broader scope of theappended claims and various obvious modifications and equivalentarrangements as would be apparent to a person of ordinary skill in theart.

What is claimed is:
 1. An organometallic compound represented by thefollowing Formula 1:

wherein in Formula 1, R₁ and R₂ are each independently a hydrogen atom,a deuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted aryl group having 6 to30 carbon atoms for forming a ring, or a substituted or unsubstitutedheteroaryl group having 2 to 30 carbon atoms for forming a ring, or arecombined with an adjacent group to form a ring, “p” is an integer of 0to 4, “q” is an integer of 0 to 3, “n” is 1 or 2, M is Pt, Ir or Os, andL₁ is a bidentate ligand.
 2. The organometallic compound of claim 1,wherein L₁ is represented by one of the following Formulae 2-1 to 2-6:

wherein in Formulae 2-1 to 2-6, X₁ is O or NR′, X₂ to X₄ are eachindependently CH, N, or NR₂₁, Y₁ is a direct linkage or CH, R′, and R₃to R₂₁ are each independently a hydrogen atom, a deuterium atom, asubstituted or unsubstituted alkyl group having 1 to 10 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atomsfor forming a ring, or are combined with an adjacent group to form aring, “a”, “c”, “d”, “e”, “g” and “j” are each independently an integerof 0 to 4, “b” is an integer of 0 to 5, “f” and “i” are an integer of 0to 3, and “h” is an integer of 0 to
 2. 3. The organometallic compound ofclaim 1, wherein M is Pt.
 4. The organometallic compound of claim 1,wherein Formula 1 is represented by one of the following Formulae 1-1 to1-3:

wherein in Formulae 1-1 to 1-3, M, R₂, L₁, “n” and “q” are the same asdefined in claim
 1. 5. The organometallic compound of claim 1, whereinthe organometallic compound represented by Formula 1 emits near-infraredrays in a wavelength region of 750 nm to 1,000 nm.
 6. The organometalliccompound of claim 1, wherein the organometallic compound represented byFormula 1 is at least one selected from compounds represented in thefollowing Compound Group 1:


7. An organic electroluminescent device, comprising: a first electrode;a hole transport region provided on the first electrode; an emissionlayer provided on the hole transport region; an electron transportregion provided on the emission layer; and a second electrode providedon the electron transport region, wherein the emission layer comprisesan organometallic compound represented by the following Formula 1:

wherein in Formula 1, R₁ and R₂ are each independently a hydrogen atom,a deuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted aryl group having 6 to30 carbon atoms for forming a ring, or a substituted or unsubstitutedheteroaryl group having 2 to 30 carbon atoms for forming a ring, or arecombined with an adjacent group to form a ring, “p” is an integer of 0to 4, “q” is an integer of 0 to 3, “n” is 1 or 2, M is Pt, Ir or Os, andL₁ is a bidentate ligand.
 8. The organic electroluminescent device ofclaim 7, wherein L₁ is represented by one of the following Formulae 2-1to 2-6:

wherein in Formulae 2-1 to 2-6, X₁ is O or NR′, X₂ to X₄ are eachindependently CH, N, or NR₂₁, Y₁ is a direct linkage or CH, R′, and R₃to R₂₁ are each independently a hydrogen atom, a deuterium atom, asubstituted or unsubstituted alkyl group having 1 to 10 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atomsfor forming a ring, or are combined with an adjacent group to form aring, “a”, “c”, “d”, “e”, “g” and “j” are each independently an integerof 0 to 4, “b” is an integer of 0 to 5, “f” and “i” are an integer of 0to 3, and “h” is an integer of 0 to
 2. 9. The organic electroluminescentdevice of claim 7, wherein M is Pt.
 10. The organic electroluminescentdevice of claim 7, wherein Formula 1 is represented by one of thefollowing Formulae 1-1 to 1-3:

wherein in Formulae 1-1 to 1-3, M, R₂, L₁, “n” and “q” are the same asdefined in claim
 7. 11. The organic electroluminescent device of claim7, wherein the emission layer comprises a host and a dopant and emitsnear-infrared rays in a wavelength region of 750 nm to 1,000 nm, and thedopant comprises the organometallic compound represented by Formula 1.12. The organic electroluminescent device of claim 7, wherein theorganometallic compound represented by Formula 1 is at least oneselected from compounds represented in the following Compound Group 1:


13. An organic electroluminescent display device, comprising: a firstpixel comprising a first organic electroluminescent device which emitsfirst visible rays; a second pixel comprising a second organicelectroluminescent device which emits second visible rays; a third pixelcomprising a third organic electroluminescent device which emits thirdvisible rays; and a fourth pixel comprising a fourth organicelectroluminescent device which emits near-infrared rays; wherein thefourth organic electroluminescent device comprises an emission layercomprising an organometallic compound represented by the followingFormula 1:

wherein in Formula 1, R₁ and R₂ are each independently a hydrogen atom,a deuterium atom, a substituted or unsubstituted alkyl group having 1 to10 carbon atoms, a substituted or unsubstituted aryl group having 6 to30 carbon atoms for forming a ring, or a substituted or unsubstitutedheteroaryl group having 2 to 30 carbon atoms for forming a ring, or arecombined with an adjacent group to form a ring, “p” is an integer of 0to 4, “q” is an integer of 0 to 3, “n” is 1 or 2, M is Pt, Ir or Os, andL₁ is a bidentate ligand.
 14. The organic electroluminescent displaydevice of claim 13, wherein L₁ is represented by one of the followingFormulae 2-1 to 2-6:

wherein in Formulae 2-1 to 2-6, X₁ is O or NR′, X₂ to X₄ are eachindependently CH, N, or NR₂₁, Y₁ is a direct linkage or CH, R′, and R₃to R₂₁ are each independently a hydrogen atom, a deuterium atom, asubstituted or unsubstituted alkyl group having 1 to 10 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atomsfor forming a ring, or are combined with an adjacent group to form aring, “a”, “c”, “d”, “e”, “g” and “j” are each independently an integerof 0 to 4, “b” is an integer of 0 to 5, “f” and “i” are an integer of 0to 3, and “h” is an integer of 0 to
 2. 15. The organicelectroluminescent display device of claim 13, wherein M is Pt.
 16. Theorganic electroluminescent display device of claim 13, wherein Formula 1is represented by one of the following Formulae 1-1 to 1-3:

wherein in Formulae 1-1 to 1-3, M, R₂, L₁, “n” and “q” are the same asdefined in claim
 13. 17. The organic electroluminescent display deviceof claim 13, wherein the organometallic compound represented by Formula1 emits near-infrared rays in a wavelength region of 750 nm to 1,000 nm.18. The organic electroluminescent display device of claim 13, whereinthe organometallic compound represented by Formula 1 is at least oneselected from compounds represented in the following Compound Group 1: